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TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 1

TRINAMIC® Motion Control GmbH & Co KG

Hamburg, Germany

www.trinamic.com

Features

The TMC249 / TMC249A (1) is a dual full bridge driver IC for bipolar stepper motor control

applications. The TMC249 is realized in a HVCMOS technology and directly drives eight external Low-

RDS-ON high efficiency MOSFETs. It supports more than 6000mA coil current. The low power

dissipation makes the TMC249 an optimum choice for drives, where a high reliability is desired. With

additional drivers, motor current and voltage can be increased. The integrated unique sensorless stall

detection (pat. pend.) stallGuard™ makes it a good choice for applications, where a reference point is

needed, but where a switch is not desired. Its ability to predict an overload makes the TMC249 an

optimum choice for drives, where a high reliability is desired. Internal DACs allow microstepping as well

as smart current control. The device can be controlled by a serial interface (SPI™i) or by analog /

digital input signals. Short circuit, temperature, undervoltage and overvoltage protection are integrated.

 More than 6000mA using 8 external MOS transistors (e.g. 4A RMS)

 Sensorless stall detection stallGuard™ and load measurement integrated

 Control via SPI with easy-to-use 12 bit protocol or external analog / digital signals

 Short circuit, overvoltage and over temperature protection integrated

 Status flags for overcurrent, open load, over temperature, temperature pre-warning, undervoltage

 Integrated 4 bit DACs allow up to 16 times microstepping via SPI, any resolution via analog control

(for up to 64 microsteps via SPI see last manual page)

 Mixed decay feature for smooth motor operation

 Slope control user programmable to reduce electromagnetic emissions

 Chopper frequency programmable via a single capacitor or external clock

 Current control allows cool motor and driver operation

 7V to 34V motor supply voltage (A-type)

 up to 58V motor supply v oltage using a few additional low cost components

 3.3V or 5V operation for digital part

 Low power dissipation via low RDS-ON power stage

 Standby and shutdown mode available

 Choice of SO28 or chip size MLF package

(1) The term TMC249 in this datasheet always refers to the TMC249A and the TMC249. The major

differences in the older TMC249 are explicitly marked with “non-A-type”. The TMC249A brings a

number of enhancements and is fully backward compatible to the TMC249.

TMC249/A – DATASHEET

High current microstep stepper motor driver

with stallGuard™, protection / diagnostics and

SPI Interface

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 2

FEATURES ............................................................................................................................................. 1

PINNING .................................................................................................................................................. 5

PACKAGE CODES ................................................................................................................................... 5

SO28 DIMENSIONS ................................................................................................................................ 6

QFN32 DIMENSIONS .............................................................................................................................. 6

APPLICATION CIRCUIT / BLOCK DIAGRAM ....................................................................................... 7

PIN FUNCTIONS ...................................................................................................................................... 7

SELECTING POWER TRANSISTORS ................................................................................................... 8

LIST OF RECOMMENDED TRANSISTORS .................................................................................................... 8

LAYOUT CONSIDERATIONS ................................................................................................................ 9

USING ADDITIONAL POWER DRIVERS ............................................................................................. 10

CONTROL VIA THE SPI INTERFACE ................................................................................................. 11

SERIAL DATA WORD TRANSMITTED TO TMC249 ..................................................................................... 11

SERIAL DATA WORD TRANSMITTED FROM TMC249 ................................................................................ 11

TYPICAL MOTOR COIL CURRENT VALUES ................................................................................................ 12

BASE CURRENT CONTROL VIA INA AND INB IN SPI MODE ....................................................................... 12

CONTROLLING THE POWER DOWN MODE VIA THE SPI INTERFACE ........................................................... 12

OPEN LOAD DETECTION ........................................................................................................................ 13

STANDBY AND SHUTDOWN MODE .......................................................................................................... 13

POWER SAVING .................................................................................................................................... 13

STALL DETECTION STALLGUARD™ ................................................................................................ 14

USING THE SENSORLESS LOAD MEASUREMENT ...................................................................................... 14

IMPLEMENTING SENSORLESS STALL DETECTION ..................................................................................... 14

PROTECTION FUNCTIONS ................................................................................................................. 15

OVERCURRENT PROTECTION AND DIAGNOSIS ........................................................................................ 15

OVER TEMPERATURE PROTECTION AND DIAGNOSIS ................................................................................ 15

OVERVOLTAGE PROTECTION AND ENN PIN BEHAVIOR ............................................................................ 15

CHOPPER PRINCIPLE ......................................................................................................................... 16

CHOPPER CYCLE / USING THE MIXED DECAY FEATURE ........................................................................... 16

ADAPTING THE SINE WAVE FOR SMOOTH MOTOR OPERATION .................................................................. 17

BLANK TIME ......................................................................................................................................... 17

BLANK TIME SETTINGS .......................................................................................................................... 17

CLASSICAL NON-SPI CONTROL MODE (STAND ALONE MODE) .................................................. 18

PIN FUNCTIONS IN STAND ALONE MODE ................................................................................................. 18

INPUT SIGNALS FOR MICROSTEP CONTROL IN STAND ALONE MODE .......................................................... 18

UNIPOLAR OPERATION ...................................................................................................................... 19

DIFFERENCES OF SHORT CIRCUIT BEHAVIOR IN UNIPOLAR OPERATION MODE ........................................... 19

DIFFERENCES IN CHOPPER CYCLE IN UNIPOLAR OPERATION MODE .......................................................... 19

CALCULATION OF THE EXTERNAL COMPONENTS ....................................................................... 20

SENSE RESISTOR ................................................................................................................................. 20

EXAMPLES FOR SENSE RESISTOR SETTINGS .......................................................................................... 20

HIGH SIDE OVERCURRENT DETECTION RESISTOR RSH ............................................................................ 20

MAKING THE CIRCUIT SHORT CIRCUIT PROOF ......................................................................................... 21

OSCILLATOR CAPACITOR ...................................................................................................................... 22

TABLE OF OSCILLATOR FREQUENCIES ................................................................................................... 22

PULL-UP RESISTORS ON UNUSED INPUTS ............................................................................................... 22

POWER SUPPLY SEQUENCING CONSIDERATIONS .................................................................................... 22

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 3

SLOPE CONTROL RESISTOR ................................................................................................................. 23

ABSOLUTE MAXIMUM RATINGS ....................................................................................................... 24

ELECTRICAL CHARACTERISTICS ..................................................................................................... 24

OPERATIONAL RANGE .......................................................................................................................... 24

DC CHARACTERISTICS ......................................................................................................................... 25

AC CHARACTERISTICS ......................................................................................................................... 27

THERMAL PROTECTION......................................................................................................................... 27

SPI INTERFACE TIMING ...................................................................................................................... 28

PROPAGATION TIMES ........................................................................................................................... 28

USING THE SPI INTERFACE ................................................................................................................... 28

SPI FILTER .......................................................................................................................................... 28

APPLICATION NOTE: EXTENDING THE MICROSTEP RESOLUTION ............................................. 29

DOCUMENTATION REVISION ............................................................................................................ 30

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 4

Life support policy

TRINAMIC Motion Control GmbH & Co KG does not

authorize or warrant any of its products for use in life

support systems, without the specific written consent

of TRINAMIC Motion Control GmbH & Co KG.

Life support systems are equipment intended to

support or sustain life, and whose failure to perform,

when properly used in accordance with instructions

provided, can be reasonably expected to result in

personal injury or death.

Information given in this data sheet is believed to be

accurate and reliable. However no responsibility is

assumed for the consequences of its use nor for any

infringement of patents or other rights of third parties,

which may result from its use.

Specifications subject to change without notice.

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 5

Pinning

TMC249 / 249A SO28

SDO

SDI

LA2HA1

INB

HA2

SRA

LA1

AGND

ANN

SLP

INA

BL2

SCK

LB1

SRB

CSN

HB1

BL1

OSC

LB2

20 GND

19 VS

18 VT

21 VCC

HB2

ENN

SPE

Note: Cooling plane on -LA type should be connected to GND or left open.

Package codes

Type

Package

Temperature range

Lead free

Code/marking

TMC249A

SO28

automotive (1)

Yes

TMC249A-SA

TMC249

SO28

automotive (1)

From date code 0505

(wwyy)

TMC249-SA

TMC249A

QFN32, 7*7mm

until date code 1808

automotive (1)

Yes

TMC249A-LA /

249A-LA

(1) ICs are not tested according to automotive standards, but are usable within the complete

automotive temperature range.

AGND

ANN

HA1

HA2

SRA

INB

ENN

CSN

SDI

SCK

SRB

LB2

LB1

HB2

HB1

BL2

BL1

Top view

LA1

LA2

32 31 30 29 28 27 26 25

910 11 12 13 14 15 16

17 18 19 20 21 22 23 24

1 2 3 4 5 6 7 8

TMC 249-LA

SPE

SDO

OSC

GND

VCC

INA

SLP

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 6

SO28 Dimensions

REF

MIN

MAX

10.65

17.7

18.1

7.4

7.6

1.4

2.65

0.25

0.1

0.3

0.36

0.49

0.4

1.1

1.27

All dimensions are in mm.

QFN32 Dimensions

REF

MIN

NOM

MAX

0.80

0.90

1.00

0.00

0.02

0.05

0.20

0.03

0.15

7.0

5.00

5.15

5.25

5.00

5.15

5.25

0.45

0.55

0.65

0.25

0.30

0.35

0.65

All dimensions are in mm.

Attention: Drawing not to scale.

-C-

SIDE VIEW PLANE

ccc C

0.08 CNX SEATING

D/2

INDEX AREA

aaa C

TOP VIEW

(D/2 xE/2)

E/2

-B-

-A-

NXL

NXb

D2/2

E2/2

bbb C A B

ddd C

-B-

-A-

NN-1

BTM VIEW

(D/2 xE/2)

INDEX AREA

SEE

DETAIL B

SEE

DETAIL B

BOTTOM VIEW WITH TYPE C ID

N-1

RADIUS

Datum A or B

DETAIL B

Terminal Tip

e/2

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 7

Application Circuit / Block Diagram

RSH

Coil A

+VM

Coil B

100µF220nF

N N

P P

TMC249

HA1

HA2

LA2

LA1

LB1

LB2

HB2

HB1

SRB

SRA

DAC

INA

INB

VREF

REFSEL

PWM-CTRL

ANNSPE

Current Controlled

Gate Drivers

Current Controlled

Gate Drivers

SLP

RSLP

PWM-CTRL

OSC

Control & Diagnosis

Parallel

Control SPI-

Interface

REFSEL

GNDAGND

Under-

voltage

Tem-

perature

OSC

VCC

1nF

100nF

+VCC

SCK

SDI

SDO

CSN

BL2BL1

[MDBN]

[PHA]

[ERR]

[PHB]

stand alone mode

[MDAN]

[...]: function in stand alone mode

ENN

VCC/2

Load

mesure-

ment

Pin Functions

Function

Motor supply voltage

Short to GND detection comparator –

connect to VS if not used

VCC

3.0-5.5V supply voltage for analog

and logic circuits

GND

Digital / Power ground

AGND

Analog ground (Reference for SRA,

SRB, OSC, SLP, INA, INB, SLP)

OSC

Oscillator capacitor or external clock

input for chopper

INA

Analog current control phase A

INB

Analog current control input phase B

SCK

Clock input of serial interface

SDO

Data output of serial interface (tri-state)

SDI

Data input of serial interface

CSN

Chip select input of serial interface

ENN

Device enable (low active), and

overvoltage shutdown input

SPE

Enable SPI mode (high active). Tie to

GND for non-SPI applications

ANN

Enable analog current control via

INA and INB (low active)

SLP

Slope control resistor. Tie to GND for

fastest slope

BL1, BL2

Digital blank time select

SRA, SRB

Bridge A/B current sense resistor input

HA1, HA2,

HB1, HB2

Outputs for high side P-channel

transistors

LA1, LA2,

LB1, LB2

Outputs for low side N-channel

transistors

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 8

Selecting Power Transistors

Selection of power transistors for the TMC249 depends on required current, voltage and thermal

conditions. Driving large transistors directly with the TMC249 is limited by the gate capacity of these

transistors. If the total gate charge is too high, slope time increases and leads to a higher switching

power dissipation. A total gate charge of maximum 25nC per transistor pair (N gate charge + P gate

charge) is recommended (at 25nC, tie pin SLP to GND to get an acceptable slope). The table below

shows a choice of transistors which can be driven directly by the TMC249. The maximum application

current mainly is a function of cooling and environment temperature. RDSon and gate charge are read

at the nominal drive voltage of 6V and 25°C.

All of these transistor types are mainly cooled via their drain connections. In order to provide sufficient

cooling, the transistors should be directly connected to massive traces on the PCB which are widened

near the transistor package, providing a copper area of some square cm. The heat then is dissipated

vertically through the PCB to a massive power or ground plane, which shall cover most of the PCB

area in order to use the whole PCB for cooling. As an example, the minimum PCB size required to

reach the given current for the SI7501, is about 42mm * 42mm, yielding in a heat up of the transistor

packages of about 85°C above ambient temperature. With a 100mm * 100mm PCB, this reduced to

70°C above ambient temperature, so that safe operation is possible up to 60°C ambient temperature at

maximum current (transistor package at 130°C).

List of recommended transistors

Manufacturer

and type

Package

(#Trans)

max. appli-

cation voltage

RDSON

[Ohm]

Total gate

charge [nC]

Typical maximum

application current

Remark

Fairchild Semi

FDD 8424 H

TO252-4

(1N,1P)

34V

0.023

0.045

6000mA

(1)

(2)

Siliconix

SI 7501 DN

PPack

(1N,1P)

28.5V

0.035

0.055

5.5

8.0

4200mA

(1)

TRINAMIC

TMC34NP

PPack

(1N,1P)

28.5V

0.035

0.055

5.5

8.0

4200mA

(1)

Fairchild Semi

FDS 8960

SO8

(1N,1P)

34V

0.023

0.050

7.0

4000mA

(1)

(2)

Fairchild Semi

FDS 8958 A

SO8

(1N,1P)

28.5V

0.023

0.050

7.0

4000mA

(2)

Siliconix

SI 4599 DY

SO8

(1N,1P)

34V

0.035

0.050

6.0

15.5

4000mA

(1)

Siliconix

SI 4532 ADY

SO8

(1N,1P)

28.5V

0.055

0.080

4.5

6.5

3000mA

5000mA (2 parallel)

(3)

Fairchild Semi

FDS 8333C

SO8

(1N,1P)

28.5V

0.075

0.130

2.9

3.0

2800mA

5000mA (2 parallel)

(3)

IRF 9952

(/ IRF 7509)

SO8

(1N,1P)

28.5V

0.075

0.280

4.5

4.0

2500mA

TRINAMIC

TMC32NP-MLP

MLP

(1N,1P)

28.5V

0.120

0.250

2.8

2.5

2300mA

4400mA (2 parallel)

very

small! (3)

Siliconix

SI 5504

1206-8

(1N,1P)

28.5V

0.090

0.170

3.0

3.2

2000mA

very

small!

TRINAMIC

TMC32NP2-SM8

SM8

(2N,2P)

28.5V

0.120

0.250

2.8

2.5

2000mA

only 2

packages!

Siliconix

SI 4559 EY

SO8

(1N,1P)

34V or

58V (see A/N)

0.045

0.120

3000mA

2500mA (at 48V)

(4)

(1) These P-channel transistors have a very high drain to gate capacity, which may introduce

destructive current impulses into the HA/HB outputs by forcing them above the power supply level,

depending on the low-side slope. To ensure reliability, connect one MSS1P3 or ZHCS1000 or an

SS14 1A Schottky diode or similar to both HA and HB outputs against VS to protect them.

(2) Compare (1), but for N-channel transistor. Protect LA/LB outputs with one Schottky diode to GND.

(3) Higher current with two devices in parallel, i.e. using 8 double transistors instead of four.

(4) See application note document for simple extension to operate at up to 58V.

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 9

Layout Considerations

For optimal operation of the circuit a careful board layout is important, because of the combination of

high current chopper operation coupled with high accuracy threshold comparators. Please pay special

attention to massive grounding. Depending on the required motor current, either a single massive

ground plane or a ground plane plus star connection of the power traces may be used. The schematic

shows how the high current paths can be routed separately, so that the chopper current does not flow

through the system’s GND-plane. Tie the TMC249’s AGND and GND to the GND plane. Additionally,

use enough filtering capacitors located near to the board’s power supply input and small ceramic

capacitors near to the power supply connections of the TMC249. Use low inductance sense resistors,

or add a ceramic capacitor in parallel to each resistor to avoid high voltage spikes. In some

applications it may become necessary to introduce additional RC-filtering into the SRA / SRB line, as

shown in the schematic, to prevent spikes from

triggering the short circuit protection or the

chopper comparator. Alternatively, a 470nF

ceramic capacitor can be placed across the

sense resistors. If you want to take advantage

of the thermal protection and diagnosis, ensure,

that the power transistors are very close to the

package, and that there is a good thermal

contact between the TMC249 and the external

transistors. Please be aware, that long or thin

traces to the sense resistors may add

substantial resistance and thus reduce output

current. The same is valid for the high side

shunt resistor. Place the optional shunt resistor

voltage divider near the TMC249, in order to avoid voltage drop in the VCC plane to add up to the

measured voltage.

+VM

GND

GND-

Plane

RSB

RSA

Bridge A Bridge B

RSH

CVM

100R

optional voltage

divider

TMC249/

TMC239A

100R

3.3 -

10nF

SRA

SRB

optional filter

AGND

GND

100nF RDIV

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 10

Using additional Power Drivers

For higher voltage and higher output current it is possible to add external MOSFET gate drivers. Both,

dedicated transistor drivers are suitable, as well as a circuit based on standard HCMOS drivers. It is

important to understand the function of dedicated gate drivers for N-channel transistors: Since the

chopping also can be stopped in open load conditions, the gate drive circuit for the upper transistors

should allow for continuous ON conditions. In the schematic below this is satisfied by attaching a weak

additional charge pump oscillator and pumping the VS up to the high voltage supply. Do not enable the

TMC249, before the gate driver capacitors are charged to an appropriate voltage. A current sensing

comparator in the VM line pulling down the VT pin by some 100mV on overcurrent can be added, if

required. Since the TMC249 in this application can not sense switch-off of the transistor gates to

ensure break-before-make operation, the break before-make-delays have to be set by capacitive

loading of its transistor drive outputs. The capacitors CdHS and CdLS are charged / discharged with

the nominal gate current. The opposite output is not enabled, before the switching-off output has been

discharged to 0.5V. To calculate the timing, refer to the required logic levels of the attached power

driver, resp. the attached PMOS. For CdHS and CdLS 470pF give about 100ns. Both circuits do not

show decoupling capacitors and further details.

High current, high

voltage MOS, e.g.

SI4450

Coil

HA1

LA1

SRA

TMC249/

TMC239

small signal P-

MOS, e.g. BSS84

+12V

LS-

Driver

+VMe.g. 50V

HS-Driver

1µF

CDHS

470p

CDLS

470p

2n2

C-Pump

20kHz

ICM7555

to other

bridges

100R

4.7nF

opt.

22K

N N

IR2101

12V

390R

SLP

10KSet HS and LS

current to 10mA

High voltage logic

level MOS bridge

Coil

HA1

LA1

SRA

TMC249/

TMC239

+VS+VM20..60V

CDHS

CDLS

1/2 74HC244

on low side

+5V

1/2 74HC244

on high side

VM-5.2V

SLP

15K set to 7 mA high-

side drive current

LM337

120R

390RADJ

OUT

55V low current

N-MOS

7..15V

100R

GND

VCC

GND

/OE

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 11

Control via the SPI Interface

The SPI data word sets the current and polarity for both coils. By applying consecutive values,

describing a sine and a cosine wave, the motor can be driven in microsteps. Every microstep is

initiated by its own telegram. Please refer to the description of the analog mode for details on the

waveforms required. The SPI interface timing is described in the timing section. We recommend the

TMC428 to automatically generate the required telegrams and motor ramps for up to three motors.

Serial data word transmitted to TMC249

(MSB transmitted first)

Bit

Name

Function

Remark

MDA

mixed decay enable phase A

“1” = mixed decay

CA3

current bridge A.3

MSB

CA2

current bridge A.2

CA1

current bridge A.1

CA0

current bridge A.0

LSB

PHA

polarity bridge A

“0” = current flow from OA1 to OA2

MDB

mixed decay enable phase B

“1” = mixed decay

CB3

current bridge B.3

MSB

CB2

current bridge B.2

CB1

current bridge B.1

CB0

current bridge B.0

LSB

PHB

polarity bridge B

“0” = current flow from OB1 to OB2

Serial data word transmitted from TMC249

(MSB transmitted first)

Bit

Name

Function

Remark

LD2

load indicator bit 2

MSB

LD1

load indicator bit 1

LD0

load indicator bit 0

LSB

always “1”

overtemperature

“1” = chip off due to overtemperature

OTPW

temperature prewarning

“1” = prewarning temperature exceeded

driver undervoltage

“1” = undervoltage on VS

OCHS

overcurrent high side

3 PWM cycles with overcurrent within 63 PWM cycles

OLB

open load bridge B

no PWM switch off for 14 oscillator cycles

OLA

open load bridge A

no PWM switch off for 14 oscillator cycles

OCB

overcurrent bridge B low side

3 PWM cycles with overcurrent within 63 PWM cycles

OCA

overcurrent bridge A low side

3 PWM cycles with overcurrent within 63 PWM cycles

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 12

Typical motor coil current values

Current setting

CA3..0 / CB3..0

Percentage of

current

Typical trip voltage of the current sense comparator

(internal reference or analog input voltage of 2V is used)

0000

0 V (bridge continuously in slow decay condition)

0001

6.7%

23 mV

0010

13.3%

45 mV

...

1110

93.3%

317 mV

1111

100%

340 mV

The current values correspond to a standard 4 Bit DAC, where 100%=15/16. The contents of all

registers is cleared to “0” on power-on reset or disable via the ENN pin, bringing the IC to a low power

standby mode. All SPI inputs have Schmitt-Trigger function.

Base current control via INA and INB in SPI mode

In SPI mode, the IC can use an external reference voltage for each DAC. This allows the adaptation to

different motors. This mode is enabled by tying pin ANN to GND. A 2.0V input voltage gives full scale

current of 100%. In this case, the typical trip voltage of the current sense comparator is determined by

the input voltage and the DAC current setting (see table above) as follows:

VTRIP,A = 0.17 VINA  “percentage SPI current setting A”

VTRIP,B = 0.17 VINB  “percentage SPI current setting B”

A maximum of 3.0V VIN is possible. Multiply the percentage of base current setting and the DAC table

to get the overall coil current. It is advised to operate at a high base current setting, to reduce the

effects of noise voltages. This feature allows a high resolution setting of the required motor current

using an external DAC or PWM-DAC (see schematic for examples).

47K

100nF

AGND

INA

INB

ANN

µC-

PWM

using PWM signal

100KµC-

Port .2

8 level via R2R-DAC

51K51K51K

100K

µC-

Port .1

µC-

Port .0

2 level control

µC-

Port

+VCC

10nF

Controlling the power down mode via the SPI interface

Standard

function

MxA

CA3

CA2

PhA

- 0 -

Control

word

function - -

Bit

Enable standby mode and

clear error flags

CA1

CA0

MxB

CB3

CB2

PhB

CB1

CB0

000 0 00 0

Programming current value “0000” for both coils at a time clears the overcurrent flags and switches the

TMC249 into a low current standby mode with coils switched off.

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 13

Open load detection

Open load is signaled, whenever there are more than 14 oscillator cycles without PWM switch off. Note

that open load detection is not possible while coil current is set to “0000”, because the chopper is off in

this condition. The open load flag will then always be read as inactive (“0”). During overcurrent and

undervoltage or over temperature conditions, the open load flags also become active!

Due to their principle, the open load flags not only signal an open load condition, but also a torque loss

of the motor, especially at high motor velocities. To detect only an interruption of the connection to the

motor, it is advised to evaluate the flags during stand still or during low velocities only (e.g. for the first

or last steps of a movement).

Standby and shutdown mode

The circuit can be put into a low power standby mode by the user, or, automatically goes to standby on

Vcc undervoltage conditions. Before entering standby mode, the TMC249 switches off all power

transistors, and holds their gates in a disable condition using high ohmic resistors. In standby mode the

oscillator becomes disabled and the oscillator pin is held at a low state. The standby mode is available

via the interface in SPI-mode and via the ENN pin in non-SPI mode.

The shutdown mode even reduces supply current further. It can only be entered in SPI-mode by pulling

the ENN pin high. In shutdown additionally all internal reference voltages become switched off and the

SPI circuit is held in reset.

Power saving

The possibility to control the output current can dramatically save energy, reduce heat generation and

increase precision by reducing thermal stress on the motor and attached mechanical components. Just

reduce motor current during stand still: Even a slight reduction of the coil currents to 70% of the current

of the last step of the movement, halves power consumption! In typical applications a 50% current

reduction during stand still is reasonable.

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 14

Stall Detection stallGuard™

Using the sensorless load measurement

The TMC249 provides a patented sensorless load measurement, which allows a digital read out of the

mechanical load on the motor via the serial interface. To get a readout value, just drive the motor using

sine commutation and mixed decay switched off. The load measurement then is available as a three

bit load indicator during normal motion of the motor. A higher mechanical load on the motor results in a

lower readout value. The value is updated once per fullstep.

The load detection is based on the motor’s back EMF, thus the level depends on several factors:

- Motor velocity: A higher velocity leads to a higher readout value

- Motor resonance: Motor resonances cause a high dynamic load on the motor, and thus

measurement may give unsatisfactory results.

- Motor acceleration: Acceleration phases also produce dynamic load on the motor.

- Mixed decay setting: For load measurement mixed decay has to be off for some time before

the zero crossing of the coil current. If mixed decay is used, and the mixed decay period is

extended towards the zero crossing, the load indicator value decreases.

Implementing sensorless stall detection

The sensorless stall detection typically is used, to detect the reference point without the usage of a

switch or photo interrupter. Therefore the actuator is driven to a mechanical stop, e.g. one end point in

a spindle type actuator. As soon as the stop is hit, the motor stalls. Without stall detection, this would

give an audible humming noise and vibrations, which could damage mechanics.

To get a reliable stall detection, follow these steps:

1. Choose a motor velocity for reference movement. Use a medium velocity which is far enough

away from mechanical resonance frequencies. In some applications even motor start / stop

frequency may be used. With this the motor can stop within one fullstep if a stall is detected.

2. Use a sine stepping pattern and switch off mixed decay (at least 1 to 3 microsteps before zero

crossing of the wave). Monitor the load indicator during movement. It should show a stable

readout value in the range 3 to 7 (LMOVE). If the readout is high (>5), the mixed decay portion

may be increased, if desired.

3. Choose a threshold value LSTALL between 0 and LMOVE - 1.

4. Monitor the load indicator during each reference search movement, as soon as the desired

velocity is reached. Readout is required at least once per fullstep. If the readout value at one

fullstep is below or equal to LSTALL, stop the motor. Attention: Do not read out the value within

one chopper period plus 8 microseconds after toggling one of the phase polarities!

5. If the motor stops during normal movement without hitting the mechanical stop, decrease

LSTALL. If the stall condition is not detected at once, when the motor stalls, increase LSTALL.

v_max

v(t)

a_max

acceleration constant velocity stall

min

max

load

indicator

stall detected!

stall threshold

vibration

acceleration

jerk

LMOVE

LSTALL

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 15

Protection Functions

Overcurrent protection and diagnosis

The TMC249 uses the current sense resistors on the low side to detect an overcurrent: Whenever a

voltage above 0.61V is detected, the PWM cycle is terminated at once and all transistors of the bridge

are switched off for the rest of the PWM cycle. The error counter is increased by one. If the error

counter reaches 3, the bridge remains switched off for 63 PWM cycles and the error flag is read as

“active”. The user can clear the error condition in advance by clearing the error flag. The error counter

is cleared, whenever there are more than 63 PWM cycles without overcurrent. There is one error

counter for each of the low side bridges, and one for the high side. The overcurrent detection is

inactive during the blank pulse time for each bridge, to suppress spikes which can occur during

switching.

The high side comparator detects a short to GND or an overcurrent, whenever the voltage between VS

and VT becomes higher than 0.15 V at any time, except for the blank time period which is logically

ORed for both bridges. Here all transistors become switched off for the rest of the PWM cycle,

because the bridge with the failure is unknown.

The overcurrent flags can be cleared by disabling and re-enabling the chip either via the ENN pin or by

sending a telegram with both current control words set to “0000”. In high side overcurrent conditions

the user can determine which bridge sees the overcurrent, by selectively switching on only one of the

bridges with each polarity (therefore the other bridge should remain programmed to “0000”).

Over temperature protection and diagnosis

The circuit switches off all output power transistors during an over temperature condition. The over

temperature flag should be monitored to detect this condition. The circuit resumes operation after cool

down below the temperature threshold. However, operation near the over temperature threshold

should be avoided, if a high lifetime is desired.

Overvoltage protection and ENN pin behavior

During disable conditions the circuit switches off all output power transistors and goes into a low

current shutdown mode. All register contents is cleared to “0”, and all status flags are cleared. The

circuit in this condition can also stand a higher voltage, because the voltage then is not limited by the

maximum power MOSFET voltage. The enable pin ENN provides a fixed threshold of ½ VCC to allow a

simple overvoltage protection up to 40V using an external voltage divider (see schematic).

ENN

µC-Port (opt.)

low=Enable,

high=Disable

+VM

for switch off at 26 - 29V:

at VCC=5V: R1=100K; R2=10K

at VCC=3.3V: R1=160K; R2=10K

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 16

Chopper Principle

Chopper cycle / Using the mixed decay feature

The TMC249 uses a quiet fixed frequency chopper. Both coils are chopped with a phase shift of 180

degrees. The mixed decay option is realized as a self stabilizing system (pat. fi.), by shortening the fast

decay phase, if the ON phase becomes longer. It is advised to enable the mixed decay for each phase

during the second half of each microstepping half-wave, when the current is meant to decrease. This

leads to less motor resonance, especially at medium velocities. With low velocities or during standstill

mixed decay should be switched off. In applications requiring high resolution, or using low inductivity

motors, the mixed decay mode can also be enabled continuously, to reduce the minimum motor

current which can be achieved. When mixed decay mode is continuously on or when using high

inductivity motors at low supply voltage, it is advised to raise the chopper frequency to minimum

36kHz, because the half chopper frequency could become audible under these conditions.

RSENSE

SWC

SWOSWC

SWO

On phase:

Current flows in target

direction

RSENSE

Fast decay phase:

Current flows back into

power supply

SWC SWO

SWO

RSENSE

Slow decay phase:

Current re-circulation

SWC SWO

SWOSWC

oscillator clock

resp. external clock

actual current phase A

target current phase A

mixed decay disabled mixed decay enabled

on slow decay on

fast decay

slow decay

When polarity is changed on one bridge, the PWM cycle on that bridge becomes restarted at once.

Fast decay switches off both upper transistors, while enabling the lower transistor opposite to the

selected polarity. Slow decay always enables both lower side transistors.

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 17

Adapting the sine wave for smooth motor operation

After reaching the target current in each chopper cycle, both, the slow decay and the fast decay cycle

reduce the current by some amount. Especially the fast decay cycle has a larger impact. Thus, the

medium coil current always is a bit lower than the target current. This leads to a flat line in the current

shape flowing through the motor. It can be corrected, by applying an offset to the sine shape. In mixed

decay operation via SPI, an offset of 1 does the job for most motors.

ITarget current

Coil current

ITarget current

Coil current

Coil current does not have optimum shape Target current corrected for optimum shape of coil current

Blank Time

The TMC249 uses a digital blanking pulse for the current chopper comparators. This prevents current

spikes, which can occur during switching action due to capacitive loading, from terminating the

chopper cycle. The lowest possible blanking time gives the best results for microstepping: A long blank

time leads to a long minimum turn-on time, thus giving an increased lower limit for the current. Please

remark, that the blank time should cover both, switch-off time of the lower side transistors and turn-on

time of the upper side transistors plus some time for the current to settle. Thus the complete switching

duration should never exceed 1.5µs. With slow external power stages it will become necessary to add

additional RC-filtering for the sense resistor inputs.

The TMC249 allows adapting the blank time to the load conditions and to the selected slope in four

steps (the effective resulting blank times are about 200ns shorter in the non-A-type):

Blank time settings

BL2

BL1

Typical blank time

GND

0.6 µs

GND

VCC

0.9 µs

VCC

GND

1.2 µs

VCC

1.5 µs

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 18

Classical non-SPI control mode (stand alone mode)

The driver can be controlled by analog current control signals and digital phase signals. To enable this

mode, tie pin SPE to GND. In this mode, the SPI interface is disabled and the SPI input pins have

alternate functions. The internal DACs are forced to “1111”.

Pin functions in stand alone mode

Stand alone

mode name

Function in stand alone mode

SPE

(GND)

Tie to GND to enable stand alone mode

ANN

MDAN

Enable mixed decay for bridge A (low = enable)

SCK

MDBN

Enable mixed decay for bridge B (low = enable)

SDI

PHA

Polarity bridge A (low = current flow from output OA1 to OA2)

CSN

PHB

Polarity bridge B (low = current flow from output OB1 to OB2)

SDO

ERR

Error output (high = overcurrent on any bridge, or over temperature). In this

mode, the pin is never tri-stated.

ENN

Standby mode (high active), high causes a low power mode of the device.

Setting this pin high also resets all error conditions.

INA,

INB

INA,

INB

Current control for bridge A, resp. bridge B. Refer to AGND. The sense

resistor trip voltage is 0.34V when the input voltage is 2.0V. Maximum input

voltage is 3.0V.

Input signals for microstep control in stand alone mode

Attention: When transferring these waves to SPI operation, please remark, that the mixed decay bits

are inverted when compared to stand alone mode.

90° 180° 270° 360°

INA

INB

PHA

(SDI)

PHB

(CSN)

MDAN

(ANN)

MDBN

(SCK)

Use dotted line to improve performance

at medium velocities

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 19

Unipolar Operation

The TMC249 can also be used in a unipolar motor application with microstepping. In this configuration,

only the four upper power transistors are required.

Differences of short circuit behavior in unipolar operation mode

Since there is no possibility to disable a short to VS condition, the circuit is not completely short circuit

proof. In a low cost application a motor short would be covered, just using the bottom sense resistors

(see schematic).

Differences in chopper cycle in unipolar operation mode

In unipolar mode, one of the upper side transistors is chopped, depending on the phase polarity. Slow

decay mode always means, that both transistors are disabled. There is no difference between slow

and fast decay mode, and the mixed decay control bits are “don’t care”. The transistors have to stand

an off voltage, which is slightly higher than the double of the supply voltage. Voltage decay in the coil

can be adapted to the application by adding additional diodes and a zener diode to feed back coil

current in flyback conditions to the supply.

HA1

LA2

SRA

TMC249/

TMC239

HA2 PP

LA1

+VM

One coil of

the motor

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 20

Calculation of the external components

Sense Resistor

Choose an appropriate sense resistor (RS) to set the desired motor current. The maximum motor

current is reached, when the coil current setting is programmed to “1111”. This results in a current

sense trip voltage of 0.34V when the internal reference or a reference voltage of 2V is used.

When operating your motor in fullstep mode, the maximum motor current is as specified by the

manufacturer. When operating in sinestep mode, multiply this value by 1.41 for the maximum current

(Imax).

RS = VTRIP / Imax

In a typical application:

RS = 0.34V / Imax

RS: Current sense resistor of bridge A, B

VTRIP: Programmed trip voltage of the current sense comparators

Imax: Desired maximum coil current

Examples for sense resistor settings

Imax

0.47

723mA

0.33

1030mA

0.22

1545mA

0.15

2267mA

0.10

3400mA

High side overcurrent detection resistor RSH

The TMC249 detects an overcurrent to ground, when the voltage between VS and VT exceeds

150mV. The high side overcurrent detection resistor should be chosen in a way that 100mV voltage

drop are not exceeded between VS and VT, when both coils draw the maximum current. In a sinestep

application, this is when sine and cosine wave have their highest sum, i.e. at 45 degrees,

corresponding to 1.41 times the maximum current setting for one coil. In a fullstep application this is

the double coil current.

In a microstep application:

RSH = 0.1V / (1.41  Imax)

In a fullstep application:

RSH = 0.1V / (2  Imax)

RSH: High side overcurrent detection resistor

Imax: Maximum coil current

However, if the user desires to use higher resistance values, a voltage divider in the range of 10 to

100 can be used for VT. This might also be desired to limit the peak short to GND current, as

described in the following chapter.

Attention: A careful PCB layout is required for the sense resistor traces and for the RSH traces.

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 21

Making the circuit short circuit proof

In practical applications, a short circuit does not describe a static condition, but can be of very different

nature. It typically involves inductive, resistive and capacitive components. Worst events are

unclamped switching events, because huge voltages can build up in inductive components and result

in a high energy spark going into the driver, which can destroy the power transistors. The same is true

when disconnecting a motor during operation: Never disconnect the motor during operation!

There is no absolute protection against random short circuit conditions, but pre-cautions can be taken

to improve robustness of the circuit:

In a short condition, the current can become very high before it is interrupted by the short detection,

due to the blanking during switching and internal delays. The high-side transistors allow a high current

flowing for the selected blank time. The lower the external inductivity, the faster the current climbs. If

inductive components are involved in the short, the same current will shoot through the low-side

resistor and cause a high negative voltage spike at the sense resistor. Both, the high current and the

voltage spikes are a danger for the driver.

Thus there are three things to be done, if short circuits are expected:

1. Protect SRA/SRB inputs using a series resistance

2. Increase RSH to limit maximum transistor current: Use same value as for sense resistors

3. Use as short as possible blank time

The second measure effectively limits short circuit current, because the upper driver transistor with its

fixed ON gate voltage of 6V forms a constant current source together with its internal resistance and

RSH. A positive side effect is that only one type of low ohmic resistor is required. The drawback is that

power dissipation increases. A high side short detection resistor of 0.33 Ohms limits maximum high

side transistor current to typically 4A. The schematic shows the modifications to be done.

However, the effectiveness of these measures should be tested in the given application.

+VM

GND

RSB

RSA

RSH

CVM

100R

SRA

SRB

GND

100nF RDIV

internal

RDIV values for reference

Microstep: 27R

Fullstep: 18R

INA/INB

up to3V

18R

12R

RSH=RSA=RSB

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 22

Oscillator Capacitor

The PWM oscillator frequency can be set by an external capacitor. The internal oscillator uses a 28k

resistor to charge / discharge the external capacitor to a trip voltage of 2/3 Vcc respectively 1/3 Vcc. It

can be overdriven using an external CMOS level square wave signal. Do not set the frequency higher

than 100kHz and do not leave the OSC terminal open! The two bridges are chopped with a phase shift

of 180 degrees at the positive and at the negative edge of the clock signal.

[nF] C s40 1

f OSC

OSC 





fOSC: PWM oscillator frequency

COSC: Oscillator capacitor in nF

Table of oscillator frequencies

fOSC typ.

COSC

16.7kHz

1.5nF

20.8kHz

1.2nF

25.0kHz

1.0nF

30.5kHz

820pF

36.8kHz

680pF

44.6kHz

560pF

Please remark that an unnecessary high frequency leads to high switching losses in the power

transistors and in the motor. For most applications a chopper frequency slightly above audible range is

sufficient. When audible noise occurs in an application, especially with mixed decay continuously

enabled, the chopper frequency should be two times the audible range.

Pull-up resistors on unused inputs

The digital inputs all have integrated pull-up resistors, except for the ENN input, which is in fact an

analog input. Thus, there are no external pull-up resistors required for unused digital inputs which are

meant to be positive.

Power supply sequencing considerations

Upon power up, the driver initializes and switches off the bridge power transistors. However, in order

for the internal startup logic to work properly, the Vcc supply voltage has to be at least 1.0V,

respectively, the Vs supply voltage has to be at least 5.0V. When Vs goes up with Vcc at 0V, a medium

current temporary cross conduction of the power stage can result at supply voltages between 2.4V and

4.8V. In this voltage range, the upper transistors conduct, while the gates of the lower transistors are

floating. While this typically does no harm to the driver, it may hinder the power supply from coming up

properly, depending on the power supply start up behavior.

There are two possibilities to prevent this from occurring:

 Add resistors from the LA and LB outputs to GND in the range of 1M keeping the low side N-

channel MOSFETs gates at GND.

 Alternatively, either use a dual voltage power supply, or use a local regulator, generating the 5V or

3.3V Vcc voltage.

Please pay attention to the local regulator start up voltage: Some newer switching regulators do not

start, before the input voltage has reached 5V. Therefore it is recommended to use a standard

linear regulator like 7805 or LM317 series or a low drop regulator or a switching regulator like the

LM2595, starting at relatively low input voltages.

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 23

Slope Control Resistor

The output-voltage slope of the full bridge is controlled by a constant current gate charge / discharge of

the MOSFETs. The charge / discharge current for the MOSFETs can be controlled by an external

resistor: A reference current is generated by internally pulling the SLP-Pin to 1.25V via an integrated

4.7K resistor. This current is used to generate the current for switching ON and OFF the power

transistors. (In non-A-type the low side slopes are fixed to typ. +/-15mA corresponding to a 5K to

10K slope control resistor!)

The gate-driver output current can be set in range of 2mA to 25mA by an external resistor:

7.4 [mA] I 123

R OUT

SLP ][k

RSLP: Slope control resistor

IOUT: Controlled output current of the low-side MOSFET driver

The SLP-pin can directly be connected to AGND for the fastest output-voltage slope (respectively

maximum output current).

Please remark, that there is a tradeoff between reduced electromagnetic emissions (slow slope) and

high efficiency because of low dynamic losses (fast slope). Typical slope times range between 100ns

and 500ns. Slope times below 100ns are not recommended, because they superimpose additional

stress on the power transistors while bringing only very slight improvement in power dissipation.

For applications where electromagnetic emission is very critical, it might be necessary to add additional

LC (or capacitor only) filtering on the motor connections.

For these applications emission is lower, if only slow decay operation is used.

-IHDOFF /

+/-ILD

RSLP [KOhm]

10520 20 50 100

IHDON

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 24

Absolute Maximum Ratings

The maximum ratings may not be exceeded under any circumstances.

Symbol

Parameter

Min

Max

Unit

Supply voltage

-0.5

VSM

Supply and bridge voltage max. 20000s

VCC

Logic supply voltage

-0.5

6.0

IOP

Gate driver peak current (1)

IOC

Gate driver continuous current

Logic input voltage

-0.3

VCC+0.3V

VIA

Analog input voltage

-0.3

VCC+0.3V

IIO

Maximum current to / from digital pins

and analog inputs

+/-10

VVT

Short-to-ground detector input voltage

VS-1V

VS+0.3V

Junction temperature

-40

150 (1)

°C

TSTG

Storage temperature

-55

150

°C

(1) Internally limited

Electrical Characteristics

Operational Range

Symbol

Parameter

Min

Max

Unit

TAI

Ambient temperature industrial (1)

-25

125

°C

TAA

Ambient temperature automotive

-40

125

°C

Junction temperature

-40

140

°C

Bridge supply voltage (A-type)

Bridge supply voltage (non-A-type)

VCC

Logic supply voltage

3.0

5.5

fCLK

Chopper clock frequency

100

kHz

RSLP

Slope control resistor

470

K

(1) The circuit can be operated up to 140°C, but output power derates.

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 25

DC Characteristics

DC characteristics contain the spread of values guaranteed within the specified supply voltage and

temperature range unless otherwise specified. Typical characteristics represent the average value of

all parts.

Logic supply voltage: VCC = 3.0 V ... 5.5 V, Junction temperature: TJ = -40°C … 140°C,

Bridge supply voltage: VS = 7 V…34 V (unless otherwise specified)

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

ILDON

Gate drive current

low side switch ON (non-A-type)

VLD < 4V

ILDOFF5

Gate drive current

low side switch OFF (non-A-type)

VLD > 3V

VCC = 5V

-15

-25

-35

ILDOFF3

Gate drive current

low side switch OFF (non-A-type)

VLD > 3V

VCC = 3.3V

-10

-15

-20

ILDON

Gate drive current

low side switch ON (A-type)

VS > 8V, RSLP= 0K

VLD < 4V

ILDOFF

Gate drive current

low side switch OFF (A-type)

VS > 8V, RSLP= 0K

VLD > 4V

-15

-25

-40

IHDON

Gate drive current

high side switch ON

VS > 8V, RSLP= 0K

VS - VHD < 4V

-15

-25

-40

IHDOFF

Gate drive current

high side switch OFF

VS > 8V, RSLP= 0K

VS - VHD > 4V

ISET

Deviation of Current Setting with

Respect to Characterization

Curve

Deviation from

standard value,

10k<RSLP<75k

100

130

VGH1

Gate drive voltage high side ON

VS > 8V

relative to VS

-5.1

-6.0

-8.0

VGL1

Gate drive voltage low side ON

VS > 8V

5.1

6.0

8.0

VGH0

Gate drive voltage high side OFF

relative to VS

-0.5

VGL0

Gate drive voltage low side OFF

0.5

VGCL

Gate driver clamping voltage

-IH / IL = 20mA

VGCLI

Gate driver inverse clamping

voltage

-IH / IL = -20mA

-0.8

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 26

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

VCCUV

VCC undervoltage

2.5

2.7

2.9

VCCOK

VCC voltage o.k.

2.7

2.9

3.0

ICC

VCC supply current

fosc = 25 kHz

0.85

1.35

ICCSTB

VCC supply current standby

0.45

0.75

ICCSD

VCC supply current shutdown

ENN = 1

µA

VSUV

VS undervoltage

5.5

5.9

6.2

VCCOK

VS voltage o.k.

6.1

6.4

6.7

ISSM

VS supply current with maximum

current setting (static state)

VS = 14V,

RSLP= 0K

ISSD

VS supply current shutdown or

standby

VS = 14V

µA

VIH

High input voltage

(SDI, SCK, CSN, BL1, BL2, SPE, ANN)

2.2

VCC +

0.3 V

VIL

Low input voltage

(SDI, SCK, CSN, BL1, BL2, SPE, ANN)

-0.3

0.7

VIHYS

Input voltage hysteresis

(SDI, SCK, CSN, BL1, BL2, SPE, ANN)

100

300

500

VOH

High output voltage

(output SDO)

-IOH = 1mA

VCC –

0.6

VCC –

0.2

VCC

VOL

Low output voltage

(output SDO)

IOL = 1mA

0.1

0.4

-IISL

Low input current

(SDI, SCK, CSN, BL1, BL2, SPE, ANN)

VI = 0

VCC = 3.3V

VCC = 5.0V

µA

VENNH

High input voltage threshold

(input ENN)

1/2 VCC

VEHYS

Input voltage hysteresis

(input ENN)

0.1

VENNH

VOSCH

High input voltage threshold

(input OSC)

tbd

2/3 VCC

tbd

VOSCL

Low input voltage threshold

(input OSC)

tbd

1/3 VCC

tbd

VVTD

VT threshold voltage

(referenced to VS)

-130

-155

-180

VTRIP

SRA / SRB voltage at

DAC=”1111”

internal ref. or

2V at INA / INB

315

350

385

VSRS

SRA / SRB overcurrent detection

threshold

570

615

660

VSROFFS1

SRA / SRB comparator offset

voltage (Standard device)

-10

VSROFFS2

SRA / SRB comparator offset

voltage (Selected device)

-6

RINAB

INA / INB input resistance

Vin  3 V

175

264

360

k

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 27

AC Characteristics

AC characteristics contain the spread of values guaranteed within the specified supply voltage and

temperature range unless otherwise specified. Typical characteristics represent the average value of

all parts.

Logic supply voltage: VCC = 3.3V, Bridge supply voltage: VS = 14.0V,

Ambient temperature: TA = 27°C, External MOSFET gate charge = 3.2nC

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

fOSC

Oscillator frequency

using internal oscillator

COSC = 1nF

1%

kHz

TBL

Effective Blank time

BL1, BL2 = VCC

1.35

1.5

1.65

µs

TONMIN

Minimum PWM on-time

BL1, BL2 =

GND

0.7

µs

Thermal Protection

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

TJOT

Thermal shutdown

145

155

165

°C

TJOTHYS

TJOT hysteresis

°C

TJWT

Prewarning temperature

135

145

155

°C

TJWTHYS

TJWT hysteresis

°C

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 28

SPI Interface Timing

Propagation Times

(3.0 V  VCC  5.5 V, -40°C  Tj  150°C; VIH = 2.8V, VIL = 0.5V; tr, tf = 10ns; CL = 50pF,

unless otherwise specified)

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

fSCK

SCK frequency

ENN = 0

MHz

SCK stable before and after CSN

change

tCH

Width of SCK high pulse

100

tCL

Width of SCK low pulse

100

tDU

SDI setup time

tDH

SDI hold time

SDO delay time

CL = 50pF

100

tZC

CSN high to SDO high impedance

tES

ENN to SCK setup time

µs

tPD

CSN high to LA / HA / LB / HB

output polarity change delay

**)

tOSC + 4

µs

tLD

Load indicator valid after LA / HA /

LB / HB output polarity change

µs

*) SDO is tristated whenever ENN is inactive (high) or CSN is inactive (high).

**) Whenever the PHA / PHB polarity is changed, the chopper is restarted for that phase. However, the chopper does not

switch on, when the SRA resp. SRB comparator threshold is exceeded upon the start of a chopper period.

Using the SPI interface

The SPI interface allows either cascading of multiple devices, giving a longer shift register, or working

with a separate chip select signal for each device, paralleling all other lines. Even when there is only

one device attached to a CPU, the CPU can communicate with it using a 16 bit transmission. In this

case, the upper 4 bits are dummy bits.

SPI Filter

To prevent spikes from changing the SPI settings, SPI data words are only accepted, if their length is

at least 12 bit.

SDO

SDI

SCK

CSN

tES

t1t1

tCL tCH

bit11 bit10 bit0

tDtZC

tDU tDH

ENN

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 29

Application Note: Extending the Microstep Resolution

For some applications it might be desired to have a higher microstep resolution, while keeping the

advantages of control via the serial interface. The following schematic shows a solution, which adds

two LSBs by selectively pulling up the SRA / SRB pin by a small voltage difference. Please remark, that

the lower two bits are inverted in the depicted circuit. A full scale sense voltage of 340mV is assumed.

The circuit still takes advantage of completely switching off of the coils when the internal DAC bits are

set to “0000”. This results in the following comparator trip voltages:

Current setting

(MSB first)

Trip voltage

0000xx

0 V

000111

5.8 mV

000110

11.5 mV

000101

17.3 mV

000100

23 mV

...

111101

334.2 mV

111100

340 mV

SPI bit

DAC bit

/B1

/B0

/A1

/A0

MDA

SPI bit

DAC bit

PHA

MDB

PHB

SRA

TMC236 /

TMC239

110R

4.7nF

opt.

74HC595

Q7'

/MR

/OE

SCK

SDI

SDO

CSN

+VCC

DS1D

100K

/CS

SDI

SCK

SDO

Free for

second

TMC239

47K 47K

47K

/DACA.0

/DACA.1

/DACB.0

/DACB.1

Vcc = 5V

1/2 74HC74

DQ Note: Use a 74HC4094

instead of the HC595 to get

rid of the HC74 and inverter

Please see the FAQ document for more application information.

TMC249 / TMC249A DATA SHEET (V2.10 / 2011-Aug-10) 30

Documentation Revision

Version

Author

BD= Bernhard Dwersteg

Description

V2.06

Added power supply sequencing considerations

V2.07

Updated logo, minor additions

V2.09

Adapted style, added info on chopper cycle

V2.10

Corrected ENN timing in SPI section, updated MOSFET list

i SPI is a trademark of Motorola